An X-ray CT (Computed Tomography) system is an apparatus that scans a subject using X-rays, then processes the acquired data by a computer in order to image the inside of the subject.
Specifically, the X-ray CT system radiates X-rays a plurality of times onto a subject from different directions along a circular orbit around the subject. The X-ray CT system detects the X-rays transmitted through the subject by an X-ray detector and acquires a plurality of detected data. The acquired detected data is transmitted to a console device, after being A/D converted by a data acquisition system. The console device applies preprocessing, etc. to this detected data to create projection data. Then, the console device carries out reconstruction processing based on the projection data and creates cross-sectional image data or volume data based on a plurality of cross-sectional image data. The volume data is a data set representing the three-dimensional distribution of CT values corresponding to the three-dimensional region of the subject.
The X-ray CT system can perform MPR (Multi Planar Reconstruction) display by rendering the above-described volume data in an arbitrary direction. Hereinafter, the cross-sectional image that is MPR-displayed via rendering of the volume data is sometimes referred to as a “MPR image.” The MPR images include, for example, axial images indicating cross-sections that are orthogonal to the body axis, sagittal images showing lengthwise sections along the body axis, and coronal images showing transverse sections along the body axis. Further, images of arbitrary cross-sections (oblique images) in the volume data are also included in the MPR images. The created multiple MPR images can be simultaneously displayed on the display part, etc.
There is an imaging method referred to as CT fluoroscopy (CTF: Computed Tomography Fluoroscopy) that uses the X-ray CT system. CT fluoroscopy is an imaging method of obtaining images relevant to region of interest of the subject in real time by continuously projecting X-rays onto the subject. According to CT fluoroscopy, images are created in real time by shortening the acquisition rate of the detected data and shortening time required for reconstruction processing. CT fluoroscopy is used, for example, in the confirmation of the positional relation between the point of a puncture needle during a biopsy and the site from which the specimen is obtained, along with the confirmation of the position of the tube when carrying out a drainage method, etc. The drainage method is a method of discharging body fluid accumulated in the body cavities using tubes, etc.
When performing a biopsy on the subject with reference to MPR images based on the volume data obtained from CT fluoroscopy, for example, scanning and puncturing may be alternately carried out. Specifically, at first, MPR images of the subject are obtained from CT fluoroscopy. Doctors, etc., carry out puncturing with reference to these MPR images. In this case, for example, in order to confirm the relational position between the point of the puncture needle and the site from which the specimen is obtained, further CT fluoroscopy is carried out when puncturing is carried out up to a certain stage. With reference to the MPR images obtained from the further CT fluoroscopy, the doctors, etc. progress further with puncturing. This operation is repeatedly carried out until the biopsy is completed.
In addition, when performing a biopsy according to CT fluoroscopy, sometimes a puncture plan is created. The puncture plan is the information including the preset an insertion route (hereinafter, sometimes referred to as a “planned route”) of the puncture needle for the subject. The puncture plan, for example, is set in CT images that have been obtained prior to carrying out CT fluoroscopy via drawing of the planned route due to the input of instructions with a mouse, etc. The doctors, etc., carry out puncturing with reference to CT images with the planned routes indicated, as well as MPR images based on the volume data obtained from each X-ray scanning.
In addition, the X-ray CT system can display images schematically indicating the volume data (hereinafter, sometimes referred to as a “viewing box”) on the display part together with the MPR images. The cross-sectional positions of the displayed MPR images (to which cross-sections of the volume data of the displayed MPR images correspond) can be displayed in the viewing box.